News– A team of scientists from Germany has developed an innovative RNA-based antiviral agent using RNA silencing that offers protection against the Cucumber Mosaic Virus (CMV)- one of the most damaging plant viruses globally.
About Cucumber Mosaic Virus (CMV)
- Type: Plant virus affecting over 1,200 plant species.
- Affected Crops: Cucumbers, melons, cereals, bananas, pumpkins, etc.
- Transmission: Spread by aphids, making outbreaks difficult to control.
- Symptoms: Mosaic discoloration, stunted growth, and poor fruit development.
- Impact in India:
- It causes 25–30% yield loss in crops like banana.
- It leads to direct economic losses and increased pest management costs.
| About RNA silencing Definition: A gene regulation mechanism where small RNA molecules (like siRNA or miRNA) bind to messenger RNA (mRNA) to:
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Working of Plant’s RNA-Based Defense Mechanism
- When a virus infects a plant, it introduces double-stranded RNA (dsRNA), which is recognized by the plant as a danger signal.
- In response, the plant activates specific enzymes called Dicer-like enzymes (DCLs). These enzymes cut the viral dsRNA into smaller fragments known as small interfering RNAs (siRNAs).
- The siRNAs act as guides, directing the plant’s immune system to identify and destroy the viral RNA, thereby preventing the virus from replicating.
- However, not all siRNAs are equally effective, and viruses often mutate rapidly, allowing them to evade the plant’s natural defenses.
RNA-based crop protection techniques against Cucumber Mosaic Virus (CMV)
- Host-induced gene silencing (HIGS)- It works by genetically modifying plants to produce virus-targeting double-stranded RNA (dsRNA) within their own cells. This offers continuous protection throughout the plant’s lifecycle.
- Cons– Its widespread use is limited due to regulatory challenges, high production costs, and the risk of viruses developing resistance.
- Spray-induced gene silencing (SIGS)- In this method, plants are treated with RNA sprays instead of being genetically modified. The leaves absorb the dsRNA, which then triggers the plant’s natural immune response without altering its DNA.
- Cons– Although SIGS is cost-effective, environmentally friendly, and does not require genetic modification, its effectiveness is short-term and may be influenced by environmental factors such as sunlight, rain, and soil microbes.
